The present invention relates to ground working tool carriers, especially those having multiple tool bars that move independently relative to one another over uneven ground surfaces.
Modern powerful farm tractors have substantially increased capability over older style equipment for pulling increased loads. This extra capability permits a much wider swath to be covered by ground working implements. Variations in soil conditions across this width present a problem where individual implements must each be precisely controlled for depth of operation, as in the case of seed drills. It is therefore desirable to provide independent control for each seed planting element and to accommodate varying terrain contour or soil hardness across the width of the swath taken by the drill. These features are especially important in "no till" farming, where both soil preparation and planting of seed are accomplished during one pass of the farm equipment.
No till farming is a relatively new method where stubble from a crop remains uncultivated during a subsequent planting and growing season. The new crop is simply planted through the stubble of the previous season's crop.
Special seed drills have been designed for this method of planting crops. An example of such a drill is discussed in U.S. Pat. No. 4,044,697. There, a heavy frame supports a seed and fertilizer hopper above a series of pivoted disc pairs. Seeds are deposited between the rotating discs and planted in furrows produced by the discs as the drill is pulled over the previous crops's stubble. A hydraulic system is provided for the pairs of discs to force the discs downwardly about an axis that is fixed relative to the carrying frame. The discs will therefore move on a radius to the pivot axis.
While this arrangement has functioned well, it is relatively inflexible as to the types and numbers of implements it can accommodate. Furthermore, only a single ground working tool can be mounted on each tool support bar due to the resulting angular movement of the bar about the fixed pivot point. Elevational movement of the ground working tool relative to the remaining tools along the length of the bar is dependent upon the radial distance to the pivot axis. Such a relationship would not be workable in uneven terrain. Additionally, downward forces applied to one ground working element cannot be as easily applied to several elements mounted along a single tool bar pivoted on a single axis. The forces applied to the several elements would vary with their relative distances from the pivot axis.
U.S. Pat. No. 3,507,233 to J. D. Greig et al discloses a seed drill making use of two ground working tools and a depth control wheel spaced longitudinally along a tool bar pivoted on a transverse horizontal axis at a forward end. The pivoted arrangement for the tool bar would not allow proper maintenance of the operating depth control in rough terrain. For example, if the implement were to approach a relatively sharp rise in the ground surface, the front implement would gouge into the elevated soil to a depth greater than the operating depth set by the trailing depth control wheel. In fact, the forward wheel could lift the entire tool bar rearward of the first ground engaging tool from the ground surface. Proper depth control would be available only when the rearward depth control wheel regains contact with the ground surface. Similar situations can occur as an abrupt dip is confronted by the forwardly moving implement. The leading ground engaging tools would either substantially decrease their operating depth or rise to an elevation above ground level until the trailing depth setting wheel descended into the recessed area. Then, the tools would either seek the prescribed depth or gouge deeply into the opposite raised side of the recess.
U.S. Pat. No. 3,749,035 to Cayton discloses a seed planter with multiple ground working tools mounted to independently pivoted longitudinal tool bars. The tool bars are attached to the main tool frame by a parallelogram linkage. The linkage causes the tool bar to remain parallel to the ground surface. This arrangement, as well as the other single pivot tool bars, might function well on level ground where the terrain is relatively smooth, but cannot operate efficiently on rough or rolling terrain. Tool frame movement might cause the tool bars to swing to orientations that have not yet been encountered by the respective trailing ground working tools. The ground engaging tools are therefore unable to effectively change position in response to terrain changes encountered by the tool bar.
The present tool bar suspension permits the mounting of several ground working tools arranged along parallel lines on multiple independently suspended tool bars. The tools can be mounted or removed at will and can also be shifted in position along the bar length. The tools mounted on one bar are free to move elevationally over terrain independently of the tools mounted on the remaining tool bars. Movement of the individual bars is controlled by their direct engagement with the terrain encountered by them. Downward forces or loading can be exerted against the tool bars without affecting their free "floating" function. The tools will therefore "walk" over uneven terrain regardless of the dowward pressure applied to them. The "walking" relationship of the floating tool bars to the general frame assures constant, precise depth control.